In recent years, mobile information terminals such as mobile phones, notebook computers and PDAs are rapidly becoming smaller and more lightweight, and batteries as power supplies for driving these devices are required to be further increased in capacity. Lithium ion batteries, which are charged and discharged by the movement of lithium ions between positive and negative electrodes, have high energy density and high capacity, and are therefore widely used as power supplies for driving mobile information terminals such as those described above.
While the capacity of lithium ion batteries is increased year by year, the batteries tend to become less reliable with increasing capacity. Thus, there is a demand that the batteries be improved in terms of the balance between high capacity and battery characteristics such as reliability.
Patent Literature 1 proposes a positive electrode for nonaqueous electrolyte secondary batteries and a nonaqueous electrolyte secondary battery utilizing the same wherein the positive electrode can suppress the occurrence of low short-circuit current between the positive electrode and a negative electrode and allows storage characteristics at high temperatures to be improved.